Apparatus for shrouding in a continuous casting machine

ABSTRACT

An expandible and retractable enclosure surrounds a molten metal stream of metal teeming from a tundish into a casting mold, and an inert gas under slight superatmospheric pressure is introduced into the enclosure. Method and apparatus are described to expand and retract the enclosure, and also to introduce the inert gas into and to hold the enclosure in an operative position against the tundish and the mold.

United States Patent [72] Inventors Henry S. Newhall Allison Park; Walter B. Thomas, Pittsburgh; Emmanuel V. Gouye, Pittsburgh, all of Pa. [21] Appl. No. 879,739 [22] Filed Nov. 25, 1969 [45] Patented Nov. 2, 1971 [73] Assignee Koppers Company, Inc.

[54] APPARATUS FOR SI-IROUDING IN A CONTINUOUS CASTING MACHINE 7 Claims, 2 Drawing Figs. [52] US. Cl 164/281, 164/259 [51] Int. Cl B22d 11/10 [50] Field of Search... 164/61, 64, 66, 281, 254, 309, 82,155, 252, 253, 256-259, 192, 337, 335, 155; 222/206, 207, 210; 266/34 V [56] References Cited UNITED STATES PATENTS 9/1959 Black 164/155 2,825,104" 3/19'58'" Joiies 164/281 X 2,889,596 6/1959 Savage 164/283 X 3,298,680 1/1967 Jablin 266/DIG. 2 3,354,941 11/1967 Halstead..... 164/283 3,439,735 4/1969 Holmes 164/259 3,482,621 12/1969 Halliday 164/281 Primary Examiner-J. Spencer Overholser Assistant Examiner-John S. Brown Attorneys-Sherman l-l. Barber, Oscar B. Brumback and Olin E. Williams APPARATUS FOR SIIROUDING IN A CONTINUOUS CASTING MACHINE BACKGROUND OF THE INVENTION It is well recognized in continuous metal casting that metals in the molten state are particularly susceptible to contamination by some gases with which they come in contact. Most metals that are continuously cast as contaminated by hydrogen in the water vapor of the ambient air, and by both oxygen and nitrogen in the air surrounding the molten metal as it teems from the tundish into the casting mod. It is further recognized that shrouding and surrounding the stream of molten metal with an inert gas eliminates the contamination of the teeming molten metal from the gases mentioned herein.

The prior art is replete with apparatus for effecting-shrouding of the molten metal during thecasting operation. But,

most of the shrouding apparatus inthe prior art is fixed in position. That is to say, it is bolted or otherwise securely fastened to the mold and to the tundish and is not adjustable in any way. That it is desirable to provide some flexibility and ad- -justability in the .shrouding apparatus is recognized; but so far as is known, the shrouding apparatus of the prior art is not constructed to allow for flexibility and adjustability.

How the shrouding apparatus and'method of the present in- I vention, overcomes the-deficiencies of the prior art apparatus and method will be recognized by one skilled in the art from the following description of one embodiment of theinvention.

SUMMARY OF THE INVENTION I An improvement in the apparatus and method for shrouding astream of metal teeming'from a tundish into a mold in a continuous casting machine comprises a collapsible and an extendible sleeve with'means for temporarily securing the sleeve to the top of the mold in a position so that the molten metal streampasses through the sleeve. Means pivotally mounted to the tundish is used to raise and lower one end ofthe sleeve for bringing it into contact with the tundish, along with means for holding the sleeve against the bottom of the tundish and against the top of the mold.

For a further description of the invention, and for-advantages and features thereof, reference may be made to the following description taken in conjunction with the drawing which shows for the purpose of exemplification one embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING DETAILED DESCRIPTION In FIG. 1 a continuous casting mold 11 of conventional form is disposed vertically beneath, and in spaced-apart relation to a tundish 13 of conventional form. The mold is vertically reciprocable in the usual manner, and the tundish 13 is provided with the usual internal flow nozzle 15 and stopper rod 17.

To the bottom of the tundish 13, along opposite bottom edges, there are secured, as by welding or in any other suitable manner, lever supporting lugs 19 each one being provided with an inverted L-shaped slot 21 located about where shown in FIG. 2.

Projecting outwardly from one vertical edge of each lug 19 is a fingerlike portion 23 that is provided with a groove 25 in the top surface; the groove being adjacent the outer end of the fingerlike portion 23. Each finger like portion 23 cooperates with a vertically movable, externally threaded hollow plunger 27 which is provided internally with a resiliently biased pin 29. A locknut 31 is threaded on the plunger 27 to secure it in any desired position.

A collapsible and extendible shroud 33 is positionable between the tundish 13 and the mold 11, as shown in the drawing, and such shroud 33 comprises a bottom circular ring 35 and a top circular ring37 to both of which is attached, as by surrounding bands 39, a bellowslike boot or open-ended tubular sleeve 41.

The bottom ring 35 is provided with a plurality of recesses 43 (though only one recess isshown) in the bottom surface each of which receives a cooperating magnet 45 that is bonded to the bottom ring 35 in a. suitable manner. The bottom ring 35 also is provided with an inlet pipe or tube 47 which extends outwardly from the ring for a purpose that will be explained hereinafter.

- The top ring 37 also cooperates witha surrounding band 39 ,to secure the upper end of the boot 41 to the top ring 37, but

the top ring does not have recesses 43 and magnets 45 like the bottom ring 35. Instead, the top ring carries outwardly extending, diametrically opposed pins 49. The .outer portion of the pins is bent downward as shown in FIG. 1. The top ring 37, like the bottom ring 35, is provided, however, with an outlet pipe or tube 51' that extends outwardly from the ring 37 as shown in FIG. 1.

The boot 41 is made preferably of high quality asbestos cloth, or the like material, and terminates at each end in a colla r that surrounds the respective bottom ring 35and top ring 37. Surrounding the collars are the: adjustable bands 39 that can be loosened and tightened by means of suitable fasteners to secure the boot to the rings.

lapsed, and it is placed on top A yoke 53, comprising outwardly extending parallel arms 55 that are connected to a tubular crossmember 5 7, is, fitted with opposed pins 59 that coact with the slots 21 in the lugs 19. A handle 61 is secured to the crossmember for manipulating the yoke 51 in the manner described hereinafter.

Each arm 55 is provided with a notch63 in the upper surface adjacent the extreme outer end of the arm, and is providedwith a lug 65 having a small detent (not shown) in its bottom surface. The lug 65 is solocated that it cooperates with the plunger 29 when the boot 41 is in its proper extended position, and when the top ring 37 is contiguous with the bottom surface of the tundish 13.

The manner in which the derstood by referring to FIG.

shroud. 33 is used may be un- 2. Initially, the shroud 33 is colof the mold 11 so that both the top and bottom rings are concentric with the mold casting cavity 67. The magnets 45 coact with and hold the bottom ring against the conventional steel cover plate (not shown) over the mold 11 to secure the bottom ring 35 in its proper position.

The pins of the yoke 53 are inserted into the slot 21 and the yoke 53 is moved by grasping the handle 61 manually and urging the yoke 53 toward the right, as viewed in FIG. 1. At the same time, the yoke is pivoted clockwise about the pins 59 to bring the arms 55 to the downwardly inclined position shown in phantom in the FIG. 2.

The yoke 53 is then maneuvered to bring the pins 49 into cooperation with the notch 63 in each arm, and then, by pivoting the yoke counterclockwise about the pins 59. the top ring 37 is raised and the shroud 33 extended. As the yoke pivots counterclockwise, at the same time it is retracted toward the left to bring the lug 65 into cooperation with the groove 25 in the top surface of the fingerlike portion 23.

With the yoke in this position, the top ring is spaced apart slightly from the bottom surface of the tundish. Then, an inert gas, preferably argon, is admitted into the shroud and the mold through conduit 47. The inert gas passes through a control valve 69 and a flexible hose 71 connected to the inlet pipe 47. Those skilled in the art will recognize that in some instances a reducing gas may also be used, but that, in most instances, an inert gas such as argon is preferred.

Argon being heavier than air and inert to most metals, particularly steel, is a preferred gas since it immediately flows downwardly into the casing cavity 67 and displaces air therein. The argon gas gradually fills the casting cavity and also the shroudthe air being released through the space between the top ring and the bottom surface of the tundish.

When all or substantially all of the air has been displaced and the argon gas fills the mold and shroud, the yoke is retracted further toward the left so that the lug 65 cooperates with the pin 29. in such cooperative position, the top ring is contiguous with the bottom surface of the tundish. Since the pin 29 is resiliently biased, it urges and maintains the top ring in the contiguous position.

Thus, the shroud forms with the tundish and the mold a contractable chamber filled with argon gas. The chamber is readily contractable and expandible as the mold reciprocates vertically in the usual manner during casting.

Thereafter, the stopper rod 17 is raised to admit molten metal into the casting cavity in the usual manner. Argon gas flows into the shroud through pipe 47 and thence from the shroud through pipe 51, flexible hose 73 and a regulator device 75.

When the casting is completed and it is desired to remove the shroud, the yoke is manipulated toward the right, as viewed in FIG. 2, and the top ring slides rightwardly also. As the ring moves to the right, it passes a groove 77 in the bottom surface of the tundish, which groove is longer than the width of the top ring. Wherefore the argon gas in the shroud, under slight superatmospheric pressure, escapes into the atmosphere. Thereupon, the shroud may be collapsed by pivoting the yoke clockwise and the shroud returns to its initial position with the top and bottom rings in contact.

Those skilled in the art will readily recognize from the foregoing description of one embodiment of the invention, several significant advantages and features among which are:

That the shroud is simple and relatively inexpensive, yet it is satisfactorily effective;

That it can be installed and removed quickly and easily; and

That in the event of an emergency that requires stopping the casting, the shroud can be collapsed quickly to permit insertion of a chill plug in the bottom of the tundish discharge nozzle.

Although the invention has been described herein with a certain degree of particularity, it is understood that the disclosure has been made as an example and that the scope of the invention is defined by what is hereinafter claimed.

What is claimed is:

l. in a machine for continuously casting a metal strand including a tundish having an outlet nozzle, and a casting mold disposed vertically below said tundish and having a casting cavity for receiving molten metal, the improvement comprismg:

a. a collapsible and extendible open-ended tubular sleeve having means extending laterally in a diametric direction at the top portion of said sleeve;

b. means for temporarily securing one end of said sleeve to the top of said mold in a position so that molten metal teeming from said tundish into said mold passes through said sleeve;

c. a yoke pivotally mounted to said tundish for engaging said laterally extending means and for raising said sleeve and for bringing the other end of said sleeve into contact with said tundish;

d. means for holding the other end of said sleeve against the bottom of said tundish; and e. means for lowering said sleeve.

2. The invention of claim 1 including:

a. means to introduce a gas into said sleeve; and

b. means to remove said gas from said sleeve.

3. The invention of claim 1 including:

a. a ring secured to each end of said sleeve; and wherein b. said means for temporarily securing one end of said sleeve includes magnets attached to one of said rings.

4. The invention of claim '3 wherein:

a. said means pivotally mounted to said tundish includes a yoke having a pair of outwardly extending arms that are adapted to cooperate with one of said rings to raise and lower said sleeve.

5. In a machine for continuously casting a metal strand including a tundish having an outlet nozzle and a casting mold disposed vertically below said tundish and having a casting cavity for receiving molten metal, the improvement comprismg:

a. a collapsible and extendible open-ended sleeve;

b. a ring secured to each end of said sleeve;

c. magnets secured to one of said rings for holding said ring in contact with said mold in a location where said molten metal teeming from said tundish flows through said sleeve into said mold;

d. a yoke pivotally mounted to said tundish and having arms adapted to engage and raise the other one of said rings;

e. means to hold said sleeve in a partially raised position with said other ring being in spaced-apart relation to said tundish;

f. means to introduce an inert gas at superatmospheric pressure into said partially raised sleeve whereby air in said mold and sleeve is displaced by said inert gas;

g. means to raise said other ring into contact with said tundish; and

h. means to temporarily hold said other ring in contact with said tundish.

6. The invention of claim 5 including:

a. means to relieve the superatmospheric pressure in said sleeve before said sleeve is retracted.

7. The invention of claim 6 wherein:

a. said means to relieve the pressure is a groove in said tundish which communicates with the atmosphere outside of and within said sleeve when said sleeve is retracted. 

1. In a machine for continuously casting a metal strand including a tundish having an outlet nozzle, and a casting mold disposed vertically below said tundish and having a casting cavity for receiving molten metal, the improvement comprising: a. a collapsible and extendible open-ended tubular sleeve having means extending laterally in a diametric direction at the top portion of said sleeve; b. means for temporarily securing one end of said sleeve to the top of said mold in a position so that molten metal teeming froM said tundish into said mold passes through said sleeve; c. a yoke pivotally mounted to said tundish for engaging said laterally extending means and for raising said sleeve and for bringing the other end of said sleeve into contact with said tundish; d. means for holding the other end of said sleeve against the bottom of said tundish; and e. means for lowering said sleeve.
 2. The invention of claim 1 including: a. means to introduce a gas into said sleeve; and b. means to remove said gas from said sleeve.
 3. The invention of claim 1 including: a. a ring secured to each end of said sleeve; and wherein b. said means for temporarily securing one end of said sleeve includes magnets attached to one of said rings.
 4. The invention of claim 3 wherein: a. said means pivotally mounted to said tundish includes a yoke having a pair of outwardly extending arms that are adapted to cooperate with one of said rings to raise and lower said sleeve.
 5. In a machine for continuously casting a metal strand including a tundish having an outlet nozzle and a casting mold disposed vertically below said tundish and having a casting cavity for receiving molten metal, the improvement comprising: a. a collapsible and extendible open-ended sleeve; b. a ring secured to each end of said sleeve; c. magnets secured to one of said rings for holding said ring in contact with said mold in a location where said molten metal teeming from said tundish flows through said sleeve into said mold; d. a yoke pivotally mounted to said tundish and having arms adapted to engage and raise the other one of said rings; e. means to hold said sleeve in a partially raised position with said other ring being in spaced-apart relation to said tundish; f. means to introduce an inert gas at superatmospheric pressure into said partially raised sleeve whereby air in said mold and sleeve is displaced by said inert gas; g. means to raise said other ring into contact with said tundish; and h. means to temporarily hold said other ring in contact with said tundish.
 6. The invention of claim 5 including: a. means to relieve the superatmospheric pressure in said sleeve before said sleeve is retracted.
 7. The invention of claim 6 wherein: a. said means to relieve the pressure is a groove in said tundish which communicates with the atmosphere outside of and within said sleeve when said sleeve is retracted. 